Set down the secateurs, silence the strimmers. Let it grow, let it grow, let it grow. Ivon Hitchens was a painter of hedgerow and undergrowth, bracken and bramble. Whoosh! go his seedlings, sprouting, bolting, demanding repotting. The first Hitchens you see on the wall outside this exhibition at Pallant House is his lithograph ‘Still Life’ (1938). A squabble of stems break bounds, vault the vase, bid for freedom. I’m a wildflower, get me out of here.

‘I love flowers for painting,’ Hitchens said. ‘Not a carefully arranged bunch such as people ought not to do — but doing a mixed bunch in a natural way.’ If his posies were ever bridal bouquets they have long since been thrown, trampled, sat on by an usher and shoved in an ice bucket to revive.

Ivon Hitchens (1893–1979) was a trier-outer. The early landscapes, such as ‘Didling on the Downs’ (1920s), are irresolute: sort of Seurat, semi-Cézanne. Hitchens’s ‘Curved Barn’ (1922) is a self-conscious tilt at Cézanne, cubism and Clive Bell’s woolly doctrine of ‘significant form’.

In the have-a-go 1920s, Hitchens dabbled with Bloomsbury — all that shrimp skin, all those bare bottoms in ‘The Pool’ (1927–8) owe something to Duncan Grant — and experimented with a style which, if not quite cubist, was certainly cub-ish. The Mr Blobby contours of Hitchens’s ‘Interiors at Barmoor Castle’ (1928) have, by the following year’s ‘Henry Moore at Work in his Studio, Parkhill Road, Hampstead’ (1929), hardened into something more dynamic and scalpel-edged.

In 1921 Hitchens exhibited with the Seven and Five Society, a changing cast of painters and sculptors committed to being uncommitted. There had of late, they argued, been too many isms, too many ‘warring sects’ and ‘too much pioneering along too many lines in altogether too much of a hurry’. The object of the Seven and Five members, according to their softly-softly manifesto, ‘is merely to express what they feel in terms that shall be intelligible, and not to demonstrate a theory nor to attack a tradition.’ So: express yourself.

Through the Seven and Five Hitchens found friendship with Ben and Winifred Nicholson. In 1925, he stayed at Bankshead, the Nicholson’s Cumberland farmhouse. His ‘Winter Hyacinths’ (c.1932) are much in Winifred’s wildflowers-and-windowsill mode, but where Winifred’s flower pieces shimmer, Hitchens’s are sludgy, the colour of jam-jar water after a day’s watercolouring.

It is in Hampstead in the 1930s, in paintings such as ‘Spring Mood no. 2’ (1933) and ‘Azaleas no. 2’ (c.1931), that everything becomes looser and more blousy. His vases still have the hard planes of cubism, but nature, stuffed into bowls, jars, teacups and stood on old plates to catch the drips, starts to sing. Music mattered to Hitchens. He could not himself play (though he liked to pretend at the guitar), but he sought in his work something he called ‘visual sound’.  He likened line, form, plane, shape, tone and colour to ‘the instruments of a painter’s orchestra’. He found an affinity with a frieze-like format in which pots, plants, urns and saucers play like notes across a stave.

The second world war forced a move to Lavington Common in West Sussex where Hitchens settled with his wife and son John in a caravan in 1940. He later built a house he called Greenleaves. In a photo taken in the woods Hitchens stands like an archer in front of his easel: Robin Hood with palette and brush for a bow and arrow. In works such as ‘Tangled Pool’ (1946) he becomes a latterday John Constable, if Constable had waded in up to his ankles and crouched for a bullrush-eye view. Some of his river paintings carry you along with the current, others leave you becalmed, still as a mill pond.

When he paints nudes with lobsterish limbs in the manner of Matisse’s odalisques you wish him back in the potting shed. It’s all about the flower power, about his gift for transforming a bottle stoppered with cuttings into a carnival of carnations and a dahlia jamboree. At his best, in works such as ‘Flowers’ (1942), Hitchens makes you reel in the hothouse haze.

Don’t miss a display in Room 6 of the permanent collection that recreates the Thirty Four Gallery, a model modern exhibition space, commissioned by the dealer Sydney Burney in 1934. Vanessa Bell, Augustus John, Cedric Morris, Paul Nash and Barbara Hepworth were invited by Burney to make miniature paintings and sculptures for a doll’s house exhibition. The tiny Hitchens, not much larger than a cook’s matchbox, is pick of the bunch.